Statistical Analysis
All statistical analyses were conducted using the statistical Platform R (vers. 4.0.1).
Sample characteristics were reported using standard descriptive statistics. Mean ± standard deviation (min to max) in case of numerical variables and absolute frequencies and percentages in case of categorical factors. Numerical variables showing highly skewed distribution were described using median with interquartile range (25th-75th percentile). Accordingly, between-group comparisons were based on the t-test or the Mann-Whitney U test in case of numerical variables and the chi-square test or the Fisher exact test in case of categorical outcome. No correction for multiple comparisons was undertaken when analyzing longitudinal outcomes (VAS score and analgesic intake).
A sample size of 30 patients for group was deemed sufficient to highlight a large effect size (d=0.8) with a power of 0.8 and a two-sided significance level of 0.05, using a Wilcoxon-Mann-Whitney U test on the primary outcome represented by the VAS score after 24h from surgery.